The final objective of this Phase II SBIR is to complete preclinical studies of a trivalent adenoviral vaccine against plague in preparation for human clinical trials. The plague vaccine project was selected in response to the growing concern surrounding the organism's possible use in a terrorism event. The NIAID and CDC, in response to this threat, has classified the organism as a Category A priority organism. Currently, there are no commercially available vaccines for protection against plague in the instance of a bioterrorism event. This concern is alarming, as multi-antibiotic-resistant strains of the plague bacterium, Y. pestis, exist in nature or have been engineered. Project Aims for this Phase II SBIR will focus on the production and evaluation of a vaccine candidate featuring the low calcium response (LcrV) antigen in combination with two other protective Y. pestis antigens, namely Caf1 (F1 capsular antigen) and YscF (a type 3 secretion system (T3SS) structural protein), in an adenoviral vector system. The project will test the hypothesis that a single, intranasal administration of the adenoviral vaccine can elicit a strong protective immune response in non-human primates (NHPs) against aerosol challenge with the fully virulent Y. pestis strain CO92. Project aims will also demonstrate the large-scale production capability of the vaccine necessary for meeting stockpiling or emergency scenarios. This program will provide a valuable first line of defense by deterrence for potential terrorists in search of weapons where no vaccine or treatment option exists. Further, the development of a multivalent adenoviral vaccine is not only significant for biodefense but also for combating global infectious disease.